Enhance CSRF protection and user management features

- Introduce CSRF token generation and management improvements, ensuring tokens are consistently retrieved from cookies or request state.
- Update user creation logic to handle validation errors more gracefully, providing user feedback for invalid input and existing email addresses.
- Revise user management UI to display success and error messages, improving user experience during user creation.
- Refactor admin user access checks to include additional role validation.

app/main.py

@@ -1,5 +1,7 @@
 from pathlib import Path
 
+from pydantic import ValidationError
+
 from fastapi import Depends, FastAPI, Form, HTTPException, Request, Response, status
 from fastapi.middleware.trustedhost import TrustedHostMiddleware
 from fastapi.responses import HTMLResponse, JSONResponse, RedirectResponse
@@ -17,7 +19,7 @@ from app.models.user import User
 from app.schemas.user import UserCreate
 from app.services.auth import get_admin_user, get_current_user, get_optional_user, require_editor_or_admin
 from app.services.config_store import get_config, set_config
-from app.services.csrf import CSRF_COOKIE_NAME, ensure_csrf_cookie, validate_csrf
+from app.services.csrf import CSRF_COOKIE_NAME, ensure_csrf_cookie, generate_csrf_token, validate_csrf
 from app.services.newsletter import (
     DEFAULT_DISPLAY,
     article_url,
@@ -62,13 +64,22 @@ def _ensure_schema_upgrades() -> None:
 
 @app.middleware("http")
 async def add_security_headers(request: Request, call_next):
+    cookie_token = request.cookies.get(CSRF_COOKIE_NAME)
+    request.state.csrf_token = cookie_token or generate_csrf_token()
+
     response: Response = await call_next(request)
     response.headers["X-Content-Type-Options"] = "nosniff"
     response.headers["X-Frame-Options"] = "DENY"
     response.headers["Referrer-Policy"] = "same-origin"
     response.headers["Content-Security-Policy"] = "default-src 'self'; style-src 'self'; script-src 'self';"
-    if not request.cookies.get(CSRF_COOKIE_NAME):
+    if not cookie_token:
-        response.set_cookie(CSRF_COOKIE_NAME, ensure_csrf_cookie(request), httponly=True, secure=cookie_secure(request), samesite="strict")
+        response.set_cookie(
+            CSRF_COOKIE_NAME,
+            request.state.csrf_token,
+            httponly=True,
+            secure=cookie_secure(request),
+            samesite="strict",
+        )
     return response
 
 
@@ -99,7 +110,7 @@ def _base_context(request: Request, user: User, db: Session) -> dict:
         active_nav = "users"
     return {
         "user": user,
-        "csrf_token": request.cookies.get(CSRF_COOKIE_NAME) or ensure_csrf_cookie(request),
+        "csrf_token": ensure_csrf_cookie(request),
         "smtp": get_smtp_settings(db),
         "active_nav": active_nav,
     }
@@ -138,7 +149,7 @@ def login_page(request: Request, db: Session = Depends(get_db)):
         request,
         "login.html",
         {
-            "csrf_token": request.cookies.get(CSRF_COOKIE_NAME) or ensure_csrf_cookie(request),
+            "csrf_token": ensure_csrf_cookie(request),
             "error_message": None,
         },
     )
@@ -159,7 +170,7 @@ def login(
             request,
             "login.html",
             {
-                "csrf_token": request.cookies.get(CSRF_COOKIE_NAME) or ensure_csrf_cookie(request),
+                "csrf_token": ensure_csrf_cookie(request),
                 "error_message": "Sitzung abgelaufen. Bitte erneut anmelden.",
             },
         )
@@ -169,7 +180,7 @@ def login(
             request,
             "login.html",
             {
-                "csrf_token": request.cookies.get(CSRF_COOKIE_NAME) or ensure_csrf_cookie(request),
+                "csrf_token": ensure_csrf_cookie(request),
                 "error_message": "Ungültige Zugangsdaten.",
             },
         )
@@ -325,14 +336,41 @@ def update_smtp_settings(
     return RedirectResponse(url="/dashboard", status_code=status.HTTP_302_FOUND)
 
 
-@app.get("/admin/users", response_class=HTMLResponse)
+def _users_context(request: Request, admin: User, db: Session, **extra) -> dict:
-def users_page(request: Request, db: Session = Depends(get_db), admin: User = Depends(get_admin_user)):
     context = _base_context(request, admin, db)
     context["users"] = db.query(User).order_by(User.created_at.desc()).all()
-    return _render(request, "users.html", context)
+    context.setdefault("error_message", None)
+    context.setdefault("success_message", None)
+    context.update(extra)
+    return context
 
 
-@app.post("/admin/users")
+def _format_validation_error(exc: ValidationError) -> str:
+    messages: list[str] = []
+    for err in exc.errors():
+        msg = err.get("msg", "Ungültige Eingabe")
+        if msg.startswith("Value error, "):
+            msg = msg[13:]
+        messages.append(msg)
+    return " ".join(messages) if messages else "Ungültige Eingabe."
+
+
+@app.get("/admin/users", response_class=HTMLResponse)
+def users_page(request: Request, db: Session = Depends(get_db), admin: User = Depends(get_admin_user)):
+    created = request.query_params.get("created") == "1"
+    return _render(
+        request,
+        "users.html",
+        _users_context(
+            request,
+            admin,
+            db,
+            success_message="Benutzer wurde erfolgreich angelegt." if created else None,
+        ),
+    )
+
+
+@app.post("/admin/users", response_class=HTMLResponse)
 def create_user(
     request: Request,
     csrf_token: str = Form(...),
@@ -343,11 +381,32 @@ def create_user(
     db: Session = Depends(get_db),
     admin: User = Depends(get_admin_user),
 ):
+    try:
         validate_csrf(request, csrf_token)
-    payload = UserCreate(email=email, full_name=full_name, password=password, role=role)
+    except HTTPException:
+        return _render(
+            request,
+            "users.html",
+            _users_context(request, admin, db, error_message="Sitzung abgelaufen. Bitte Seite neu laden und erneut versuchen."),
+        )
+
+    try:
+        payload = UserCreate(email=email.strip(), full_name=full_name.strip(), password=password, role=role)
+    except ValidationError as exc:
+        return _render(
+            request,
+            "users.html",
+            _users_context(request, admin, db, error_message=_format_validation_error(exc)),
+        )
+
     existing = db.query(User).filter(User.email == payload.email).first()
     if existing:
-        raise HTTPException(status_code=400, detail="E-Mail existiert bereits.")
+        return _render(
+            request,
+            "users.html",
+            _users_context(request, admin, db, error_message="Diese E-Mail-Adresse ist bereits registriert."),
+        )
+
     user = User(
         email=payload.email,
         full_name=payload.full_name,
@@ -358,4 +417,4 @@ def create_user(
     )
     db.add(user)
     db.commit()
-    return RedirectResponse(url="/admin/users", status_code=status.HTTP_302_FOUND)
+    return RedirectResponse(url="/admin/users?created=1", status_code=status.HTTP_302_FOUND)

app/services/auth.py

@@ -36,7 +36,7 @@ def get_current_user(request: Request, db: Session = Depends(get_db)) -> User:
 
 
 def get_admin_user(current_user: User = Depends(get_current_user)) -> User:
-    if current_user.role != "admin":
+    if current_user.role != "admin" and not current_user.is_admin:
         raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Admin-Rechte erforderlich.")
     return current_user
 

app/services/csrf.py

@@ -7,13 +7,21 @@ CSRF_COOKIE_NAME = "csrf_token"
 CSRF_FORM_FIELD = "csrf_token"
 
 
-def ensure_csrf_cookie(request: Request) -> str:
+def generate_csrf_token() -> str:
-    token = request.cookies.get(CSRF_COOKIE_NAME)
-    if token:
-        return token
     return secrets.token_urlsafe(32)
 
 
+def ensure_csrf_cookie(request: Request) -> str:
+    """Liefert das CSRF-Token für die aktuelle Anfrage (Cookie oder request.state)."""
+    state_token = getattr(request.state, "csrf_token", None)
+    if state_token:
+        return state_token
+    cookie_token = request.cookies.get(CSRF_COOKIE_NAME)
+    if cookie_token:
+        return cookie_token
+    return generate_csrf_token()
+
+
 def validate_csrf(request: Request, form_token: str) -> None:
     cookie_token = request.cookies.get(CSRF_COOKIE_NAME)
     if not cookie_token or not form_token or not secrets.compare_digest(cookie_token, form_token):

app/templates/users.html

@@ -13,6 +13,12 @@
             <div class="card-header">
                 <h3>Neuen Benutzer anlegen</h3>
             </div>
+            {% if error_message %}
+            <p class="error">{{ error_message }}</p>
+            {% endif %}
+            {% if success_message %}
+            <p class="hint" style="color:var(--tk-success);font-weight:600;">{{ success_message }}</p>
+            {% endif %}
             <form method="post" action="/admin/users" class="form-grid">
                 <input type="hidden" name="csrf_token" value="{{ csrf_token }}">
                 <div class="form-row">
@@ -25,7 +31,7 @@
                 </div>
                 <div class="form-row">
                     <label>Passwort
-                        <input type="password" name="password" required minlength="10">
+                        <input type="password" name="password" required minlength="10" placeholder="Mindestens 10 Zeichen">
                     </label>
                     <label>Rolle
                         <select name="role">